The present invention relates to a landing control system suitable for controlling the operation of a lift or elevator.
One of the most significant operational problems arising in high use multi-story elevator installations concerns the landing control system by which the elevator makes an appropriate and specific stop at the floor or landing selected by the user. As is known, the elevator car is lifted and lowered through a shaft by a hoist mechanism as it rides on continuous vertical rails constituting a hoist way. Various landing systems have been applied to such basic structure to arrest the car movement at selected floors.
In U.S. Pat. No. 2,674,348 to Santini et. al., an elevator system is disclosed in which inductor plates mounted along the elevator shaft are detected by sensors mounted on the elevator to initiate deceleration and leveling. A major disadvantage of this system is that it requires very close tolerances in order to insure proper alignment. These close tolerances make maintenance of the system difficult and costly. In addition, alteration of the system is complex, requiring the system to be shut down for long periods.
U.S. Pat. No. 2,840,188 to Savage discloses a system in which magnetic plates are mounted on a nonmagnetic ribbon which extends the length of the elevator shaft. Although this system makes maintenance somewhat easier, the removal and replacement of the magnetic plates remains costly. Again, alteration requires lengthy downtime at a significant cost to the user.
In U.S. Pat. No. 4,203,506 to Richmon an elevator control system is disclosed in which a magnetic target material is wrapped around a nonmagnetic wire. The magnetic target material triggers a sensor contained within the sensor housing. A major disadvantage of this system is the frictional wear inflicted upon the magnetic material due to the repetitive contact of the housing. This wear necessitates the replacement the magnetic target material, which can be costly, requiring the uncrimping of the soft metal target material. This can be a tedious and time consuming process, making the system particularly unsuited to on-site alteration.
It is, therefore, the object of the present invention to provide a landing control system that is accurate in its deceleration and stopping. It is a further object of the present invention to provide a system that minimizes wear on the rail and/or car and allows for simple on-site alteration, reconstruction and repair.
These objects, as well as others, will be apparent from the following disclosure of the present invention.